CHEMICAL BASIS OF LIFEAT THE CELLULAR LEVEL:

CHEMISTRY BECOMES

BIOLOGY-body functions depend on cellular functions

-cellular functions result from chemical changes

-biochemistry helps to explain physiological processes, and develop new drugs and methods for treating diseases

STRUCTURE OF MATTER

• MATTER- ANYTHING THAT HAS WEIGHT AND TAKES UP SPACE

ELEMENTS AND ATOMS• ELEMENT- THE BASIC SUBSTANCE OF MATTER

– Living organisms require about 20 elements• 65%- Oxygen• 18.5%- Carbon • 9.5%- Hydrogen • 3.2%- Nitrogen• 5%- Other

• ATOM- TINY PARTICLES THAT MAKE UP ELEMENTS– THE SMALLEST COPLETE UNITS OF ELEMENTS– ATOMS OF AN ELEMENT ARE SIMILAR TO EACH, BUT

DIFFERENT FROM THOSE OF ANY OTHER ELEMENT

Atomic StructureAtoms - composed of subatomic particles:

• protons – carry a positive charge

• neutrons – carry no electrical charge• electrons – carry a negative charge

Nucleus• central part of atom• composed of protons and neutrons• electrons move around the nucleus

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Atomic Number and Atomic Weight

Atomic Number • number of protons in the nucleus of one atom • each element has a unique atomic number• equals the number of electrons in the atom

Atomic Weight• the number of protons plus the number of neutrons in one atom • electrons do not contribute to the weight of the atom

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Molecules and Compounds

Molecules – particle formed when two or more atoms chemically combine

Compound – particle formed when two or more atoms of different elements chemically combine

Molecular formulas – depict the elements present and the number of each atom present in the molecule

H2 C6H12O6 H2O

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Structural Formula

Structural formulas show how atoms bond and are arranged in various molecules

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Chemical Reactions

Chemical reactions occur when chemical bonds form or break among atoms, ions, or molecules

Reactants are substances being changed by the chemical reaction

Products are substances formed at the end of the chemical reaction

NaCl Na+ + Cl-

Reactant Products

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Types of Chemical Reactions

Synthesis Reaction – chemical bonds are formed A + B AB

Decomposition Reaction – chemical bonds are brokenAB A + B

Exchange Reaction – chemical bonds are broken and formed AB + CD AD + CB

Reversible Reaction – the products can change back to the reactants

A + B AB

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Acids, Bases, and Salts

Electrolytes – substances that release ions in water

Acids – electrolytes that release hydrogen ions in waterHCl H+ + Cl-

Bases – substances that release ions that can combine with hydrogen ions

NaOH Na+ + OH-

Salts – electrolytes formed by the reaction between an acid and a base

NaCl Na+ + Cl-

HCl + NaOH H2O + NaCl

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Acid and Base ConcentrationspH scale - indicates the concentration of hydrogen ions insolution

Neutral – pH 7; indicates equal concentrations of H+ and OH-

Acidic – pH less than 7; indicates a greater concentration of H+

Basic or alkaline – pH greater than 7;indicates a greater concentration of OH-

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Organic Versus InorganicOrganic molecules

• contain C and H• usually larger than inorganic molecules• dissolve in water and organic liquids• carbohydrates, proteins, lipids, and nucleic acids

Inorganic molecules • generally do not contain C• usually smaller than organic molecules• usually dissolve in water or react with water to release ions• water, oxygen, carbon dioxide, and inorganic salts

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Inorganic SubstancesWater

• most abundant compound in living material• two-thirds of the weight of an adult human• major component of all body fluids• medium for most metabolic reactions• important role in transporting chemicals in the body• can absorb and transport heat

Oxygen (O2) • used by organelles to release energy from nutrients• necessary for survival

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Carbon dioxide (CO2)• waste product released during metabolic reactions• must be removed from the body

Inorganic salts• abundant in body fluids• sources of necessary ions (Na+, Cl-, K+, Ca2+, etc.)• play important roles in metabolic processes

Organic Substances- Carbohydrates

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• provide energy to cells •supply materials to build cell structures •water-soluble •ratio of H to O close to 2:1 (C6H12O6) •monosaccharides – glucose, fructose •disaccharides – sucrose, lactose •polysaccharides – glycogen, cellulose

Organic Substances Lipids

• soluble in organic solvents

• fats (triglycerides)• used primarily for energy• contain C, H, and O but less O than carbohydrates (C57H110O6)• building blocks are 1 glycerol and 3 fatty acids per molecule• saturated and unsaturated

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Organic Substances Lipids• phospholipids

• building blocks are 1 glycerol, 2 fatty acids, and 1 phosphate per molecule

• hydrophilic and hydrophobic

• major component of cell membranes

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Organic Substances Lipids• steroids

• connected rings of carbon• component of cell membrane• used to synthesize hormones• cholesterol.

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Organic Substances Proteins• structural material• energy source• hormones• receptors• enzymes• antibodies • building blocks are amino acids

• amino acids held together with peptide bonds

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Organic Substances ProteinsFour Levels of Structure

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Organic Substances Nucleic Acids

• constitute genes• play role in protein synthesis

• building blocks are nucleotides

• DNA (deoxyribonucleic acid) – double polynucleotide• RNA (ribonucleic acid) – single polynucleotide

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Organic SubstancesNucleic Acids

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